Conventional vehicle transmissions predominantly employ wet clutches to accomplish gear shifting. Transmissions typically include a transmission fluid which is recycled throughout the transmission. Wet clutches generally provide greater heat transfer and temperature control than dry clutches. Wet clutches also, however, have a lower coefficient of friction than dry clutches. Wet clutches are further known to slip pre-engagement.
Dry clutches tend to provide higher coefficients of friction than wet clutches. Dry clutches can provide lower costs and complexity. Still, dry clutches can have thermal management issues. For example, dry clutches can reach higher temperatures in repeat vehicle launch events with heavy vehicle load and road grade conditions. Some existing designs have attempted to reduce transmission heating in wet clutch transmission. U.S. Pat. No. 6,568,518 titled “Clutch for a Power Train of a Motor Vehicle” discloses a clutch having fan blades configured to generate an air stream over the surface of the flywheel. The blades disclosed are flowing in a single direction which produces a relatively undisturbed fluid flow path. A more viscous flow would yield greater heat transfer.
Therefore, it is desirable to have a dry-clutch transmission with improved heat transfer techniques.